The peak curvature frequency is determined by \(\gamma _{\rm eff}\) .
When \(\gamma _{\rm gr} < \gamma _{\rm geom}\) , the soliton behaves like a point emitter and the energy spectrum
\(\omega \cdot d^2E_c/d\omega dt\)  peaks at [1]}
\((\omega _c^{\rm peak,\perp },\;\omega _c^{\rm peak\parallel }) \sim (0.47,\;0.69)\,{\gamma _{\rm gr}^3c\over R_c} \;=\; (1.1,\;1.6)\left({\gamma _{\rm gr}\over \gamma _{\rm geom}}\right)^3 {c\over l_z}\quad \quad (\gamma _{\rm gr} < \gamma _{\rm geom}).\) 
